Automatically-controlled switch device



J n. l 1927.

a l R. J. PATTERSON AUTOMATICALLY CONTROLLED SWITCH DEVICE vFiled July 9, 1923 our our -JZH//l/l/l Il Patented Jan. 1l, 1927.

UNITED STATES PATENT GFFICE.

RALPH J. PATTERSON, 0F WATEBTGWN, MASSACHUSETTS, ASSIGOB T0 WALKER PRATT MANUFACTURING COIPANY, OF BOSTON, MASSACHUSETTS, A CORPORA-v TION 0F MASSACHUSETTS.

Appleman ma July s, 192s. semi no. escaso.

This invention relates to automatically controlled electric switches, and possesses `features of novelty and advantage which are particularly adapted for use in controlling, through electrical means, devices such as electric heaters or ranges.

One object of theinvention is to provide an improved form and arrangement of parts for an electrical switch to be controlled by external conditions of temperature, pressure,

changes in level of liquids,'or the like, which,y

is sensitive, accurate, and positive in operation in any position.

Another object of the invention is to provide an improved form of thermostaticallv operated switch which cannot become in- 4jured by excessive movements of the thermostatic responsive means, due to extreme temperatures.

Another object of the invention is to provide au improved form of thermostatically controlled electric switch which may be easily adjusted to' operate within any desired range of temperatures and which may be quickly set so as to operateI at any prede-- termined temperature within the selected range.

AY further object is to provide a device of this sort which is characterized by its ex-` treme simplicity'andcompactness in construction, its sturdiness, and by its effectiveness in operation.

Other objects of the invention will be in part obvious and in part pointed out here-y inafter.

The invention accordingly consists in the features of construction, combination of elements and arrangement of parts 'which will be exemplified in the construction hereinafter set forth, and the scope of the application of which will be indicatedl inthe appended claims.

In the drawings forming a part of the specification and in which similar reference characters refer to similar parts,

Fig. 1 is an elevational view showingonc form which the present invention may take;

Fig. 2 is a vertical sectional view thereof; and v Fig. 3 is a view taken substantially on line 3-3 of Fig. l. l

Referring to the drawings in detail, my improved apparatus, includes an electrical switch having a casing or housing 9 Within which is ivoted, as at 10, a switch arm 11 adapted ,or alternate engagement with the stationary terminals or contacts 12 and 13. These stationary contacts may be placed closely together so that the throw of the switch arm is very slight; that is to say, when the switch arm is moved it leaves one contact and then engages the other one. These stationary contacts may be electrically connected to a solenoid operated switch, which controls the heating element of a range for instance, in such manner that when the switch arm engages the upper contact 13, the remote switch is operated to throw the current onto the heating element of a range or oven, and the current through the contact 13 is broken; and -when the switch arm is thrown into engagement with the other contact 12, the remote switch is opened to throw the heat off of the oven, and the circuit is broken through thereontact 12, The movement of the switch arm 11 is controlled by suitable responsive device which is here shown asbeing in the form of a thermostat, as the features of the presentinvention are peculiarly adapted to thermostatically control electric switches. This thermostat may comprise a metal tube 14 constructed of a material having a relatively high coefficient of expansion and a rod 15 therein of Ya material relatively noncxpansible with heat changes, for instance carbon. The tube 14 is closed at its lower end and is preferably threaded into a boss 16 depending from the housing 9 so that the thermostat may be removed without disturbing the adjustment of the switch. When the tube 14 is heated, it is elongated so that the carbon rod is lowered, and when the tube cools off, it becomes shorter and raises the carbon rod. lThis thermostatic device controls movement of the switch arm 11 through a plunger 2O having at its lower end a head 21 which rests upon but is not connected to the top of the carbon rod 15. The plunger is normally urged downwardly towards the rod 15 by a coiled spring 22 abutting at its opposite ends against the housing 9 and the head 21. The plunger has a sliding movement in the openings of the housing through which it passes and is held against rotation by the splines or keys 23 operating Cri CII

in the grooves 24. The switch arm is normally urged upwardly into engagement with the contact 13 by means ot a suitable spring which, it desired, may take the form of a leat spring, such as designated by the numeral in the drawings. lt will be noted, particularly trom Figs. 2 and 3, that the plunger has an elongated vertical slot o'f opening 26 through which the switch arm 11 extends.

Mounted for adjustment, tor the purpose hereinafter described more in detail, within the upper end et the plunger 2() and extending down int-o the. slot 26, is a threaded pin or screw 27 which is adapted to bear against that side ot the switch arm opposite to that ot the spring 25, that is to say on the top ot the switch arm. There is a considerable clearance 28 between the lower side of the switch arm and the plunger so that the plunger will have no upward thrust against the switch arm and injure the mechanism when the tube 14 is oreshortened upon cooling eti?. Also, this clearance allows considerable lee-way in the matter of adjustment. rlhe screw 27, which forms the onlyconnection or engagement between the plunger and the switch arm, is preliminarily adjusted within the plunger to vary the effective length thereot and thereby determine the range of temperatures within which the thermostatic device will actuate the switch. ln order to set or regulate this pin longitudinally ot the plunger within the selected range, so that the thermostatic device will result in actuation of the switch at any desired predetermined temperature within that range, there is associated with this screw 27 what may be termed a regulating devlkce which is shown here in the forrnot a sleeve 30 having an indicating member in the form ot a pointer 31 adapted to move over position indicating means, such as a scale 32, carried by the housing 9. In the present illustrative discosure ot the invention, the sleeve 30 is externally threaded and is screwed, tor longitudinal adjustment, into the threaded recess 33 in the upper end of the plunger 20. The sleeve is internally threaded so as to receive the pin 27, as shown most clearly in Figs. 2 and 3.

Preferably. the switch parts are carried b v a stationary plate 35 of insulating material suitably secured to a housing. The contacts 12 and 13 are directly mounted on this plate. The free end of the switch arm is insulated trom the pivoted end by a connection 36 ot insulating material. The tree end ot the switch arm is connected to a` suitable conductor 3T. Connected respectively to the contacts 12 and 13 are the conductors 3S and 39 which may lead to suitable controlling mechanism, such as has been previously described.

The operation ot the device will be readily Laietana understood. The ran e of temperature within which it is desired that the device operate, having been selected depending on conditions, the pointer 31 will be set on the scale 32 to indicate 'a predetermined temperature within the selected range, and then the thermostatic device is heated up (as by placing it within a chamber, the temperature of which can be accurately controlled) to a temperature corresponding to that indicated by the pointer 31 on the scale 32. The screw 27 will then be adjusted relatively to the sleevel 30 .so that when the thermostatic device has been heated up to the predetermined temperature, the screw will engage and throw the switch arm 11 downwardly to close the circuit through the lower contact 12. lt will now be clear that, by so manually adjusting the screw 2i relative to the regulating means, including in part the pointer 31, the range ot temperature within which the thermostat will actuate the switch arm is determined. To set the device so that the switch arm will be thrown at any desired predetermined temperature within the selected range, it is merely necessary to move the pointer 31 into registry with that indicating mark of the scale 32 which designates that predetermined temperature. ln so moving the pointer 31, it is obvious that the sleeve, together with the adjusting screw 2i' carried thereby, will move up or down, as the case may be, within the plunger and thereby change the eliective length or distance between the operative end of the screw 27 and the top ot the thermostatic member 15.

rl"he device, having been adjusted as just described, and, assuming that the screw 27 has been adjusted relative to the sleeve 30 so that the effective range of temperature is between 400 and 600 degrees, and that the pointer 31 has been set on the mark indicating '-150 degrees, it will be seen that when thc oven. tor instance, to which the device is applied reaches a temperature ot 450 degrees. the tube 14 will have been elongated to such an extent that the plunger is lowered to a point where the lower end otl the adjusting screw 2? engages and depresses the switch arm 11, thereby throwing the same from engagement with the upper contact 13 into engagement with the lower contact 12. Assuming that the improved mechanism herein shown is used in combination with the heating element of an oven, the current on this heating element may be thrown oit' when the switch arm engages the contact l2 and. at the same time, the current through the switch arm and the contact 12 may be broken. Should the oven continue to heat up after the switch arm 11 has been thrown downwardly, as just described. no damage can result to the switch parts, for the head 21 ot the plunger rests upon but is not connected ill) Uil

lll"

- plunger will be raised to move the screw 27 out of engagement with the switch arm and then this switch armyunder the influence of the spring 25, will be thrown into engagement with the contact 13, and the contro ling mechanism with which the switch is associated will throw the current onto the heating element. Should the temperature ofthe oven fall below 450 degrees, in which event the tube 14 would be further foreshortened, no injury or jamming of the switch would result because of the clearance 28 between the switch arm and the plunger.

- when the temperature of the oven rises, and

will operate the switch arm 11 to throw the current onto the heating elementl when the temperature falls to 450 degrees.

From the foregoing descriptiomit will be seen that my improved device is characterized by its cxtreme simplicity in 'construction and arrangement and, therefore, it may be manufactured at a relatively low cost while, at the same time, it is sufliciently strono' and sturdy to withstand the duty placed upon it. It is particularly effective in operation in that it is extremely sensitive to changes in the responsive or actuating device, and it may be quickly and accurately set to operate at an desired temperature. The switch arm is tlirown downwardly by the spring 22 and is thrown upwardly by the spring 25 so that at no time is there an excessive force exerted against the switch arm which means that the same will not be injured or jammed, and this is a matter of particular importance because the throw of the switch arm `trom one contact to the other is very slight. The movable switch member or part thereof, in the present instance the switch arm 11, passes through an opening' in the plunger immediately beneath the adjusting screw 27 which makes for simplicity, and gives a direct thrust on the switch arm so that there is no tendency for the parts to cant or be thrown out of alinement. The device may be `set by turning'the screw 27 within the sleeve 3@ so as to operate within any desired range, and the setting of the device so as to operate at any one predetermined temperature within the selected range may be readily made by merely bringing the pointer 31 into proper position relative to the scale 32.

I claim as my invention:

1. In an apparatus of the character described, an electrical switch having a pair of contacts and a pivoted member between said contactsY adapted to move from engagement with one into engagement withlthe other thereof; actuating means for said member including an element movable towards and 'away from said pivoted member, a connection between said pivoted member and element including a plunger movable relative to said member and element and engaging said member on the side opposite said element, said plunger being positively moved by said element only when the latter moves towards said pivoted member, said plunger being movable out of engagement with said member when the latter engages one of said contacts and said element has moved said plunger to 'a predetermined extent, said plunger being supported on said member free of said element when said member en gages the other of said contacts, and a spring normally urging said pivoted member in the direction in which said plunger is positively moved by said element.

2. In an apparatus of the characer described, an electrical switch having a pair of contacts and a pivoted member therebe tween movable from engagement with one of said contacts into engagement with theother;` actuating means for said member including an element movable towards and away from said pivoted member, a connection between said pivoted member and element including a plunger movable relative to said member and element, an adjustable part on said plunger engaging said member on the side opposite said element, said plunger being positively moved out of engagement with said element ywhen said element has moved said plunger to a predetermined extent where said member engages one of said contacts, said plunger being supported free of said element by said member when the latter engages the other of said contacts. and a spring normally urging said pivoted member in the direc'ion in which. said plunger is positively moved by said element.

3. In an apparatus ot the character described, an electrical switch having a pivoted member, a temperature responsive device including a part having a relatively high coeicient of'expansion and a rod having a relatively low co-eiicient of expansion, a plunger loose of but engaging said rod, means adjusably carried by said plunger and engaging said member on the side opposite said rod, and a spring normally urging said plunger into engagement with said rod. f

4. In an .apparatus the character described, a circuit` controlling switch having a pair of slightlyv spaceduapa'rt contacts and circuit closinv'mcans including an arm; a thermostatlc device including a part having a relatively high' co-eiicient of expansion and a rod having a relatively low co-emcient of expansion;` a lunger having its inner end engaging .but oose of said rod and h aving at its `intermediate porton an opening through which "said"arn'iextends; and an adjustable screwin the'outer end of said plunger engaging said arm on that side opposite to said thermostatic device.

5. In an apparatus of the character described, a circut controlling switch including a pivoted arm, a change responsive device, a plunger constituting a connection between said arm and device, a member on the outer end ot' said plunger and engaging said arm on that side opposite te said .devce, said member being longitudinally adjustable on -said plunger to determine the range of temperature within which said apparatus may operate, and temperature indicating mechanism including a part adjustable with respect to said member and adapted to adjust the same to any desired temperature Within the selected range.

6. ln an apparatus ot' the character dcscribed, a switch including a pair of slightly spaced apart contact members and circuit closing means adapted to move between said contacts and including an arm; a thermostat'c device; a plunger constituting a connection between said device Vand arm and including a screw engaging said arm: and temperature indicating means including a part angularly adjustable with respect to said rc1-ew, and adapted to turn and thereby set the same.

7. ln an apparatus of the character described. a switch including a pivoted member, a change responsive device, a connection therebetween, a rotatable screw for varying the eective length of said connection to determine the range of operation, a temperature indicating mechanism for setting sa'd screw to any desired point within the selected range and including a scale element and an indicating element-` said rotatable screw being adjustable'with respect te one ot said elements to determine the '.set thedervicev to operate at range of operation and being rotatable'with slaidelem'en't when the latter-"is 'rotated to agiven point inthe selected range.

8. In an apparatus of the character "described, an electrical switch having a pivoted member, actuating means therefor includinffan element movable towards and away rom said pivoted member, a connectio'n between" said pivoted member and element including a' plunger movable relative to said member and element, an adjustable part on said plunger engaging Said member on the side opposite said clement, said plunger being positively moved out of engagement with said member when said element has moved said plunger to a predeterm'ned extent, a spring normally urging Said pivoted member in.the direction in which said plunger 'is positively movedl by said element, and temperature indicating mechanism for adjusting sa'd part and including a scale-element and an indicating element, one ot'fwhich elements is adjustably connected to said adjustable part for the purpose described.

9. In an apparatus of the character ldescribed, a circuit controllingswitch arm normally urged into one circutI making position, a thermostat, va spring pressed member operatively associated with said thermostat and adapted to move said arm to another circuit making position, said member being nrovded with an adjustable screw to contact with said arm, a sleeve supporting said screw and threaded into said menibci, and means for rotating said sleeve- 10. ln an apparatus ot' the character described, a base or housing, a switch thereon having an arm, a spring normally urging said arm into one e'rcuit controlling position, a plunger operatively associated with said switch arm, a thermostat. a second spring adapted to press said plunger into Contact with said thermostat, a rotatable threaded sleeve in said plunger, a screw carried by said sleeve and adapted to press aganstsaid switch arm in a direction against the torce ot the tirst said spring. a scale on said base, and a lever carried by -said sleeve and movable over said scale.

RALPH J. PATTERSON. 

